1. Field of the Invention
The invention relates to an image forming apparatus such as a printer or the like having a function for printing images onto both surfaces of a recording medium or a function for printing an image onto the same surface a plurality of number of times.
2. Related Background Art
In a conventional image forming apparatus using a heat fixing system, such a phenomenon that the moisture contained in a recording medium is evaporated by the heat of the thermal fixing and the recording medium is contracted after the fixing occurs. Therefore, in the case of printing images onto both surfaces of the recording medium or in the case of printing an image onto the same surface a plurality of number of times, after the image printed first was fixed, the image of the second time is transferred, so that a size of image printed first and a size of image printed at the second time differ. Therefore, particularly, in the case where the same image is printed onto both surfaces or onto the same surface, or the like, an inconvenience that a positional change of the same image is apt to be conspicuous occurs.
To solve such a problem, a technique in which against contraction of the recording medium that is caused by an influence of heat fixing, a correction value of print contents corresponding to such contraction is preset and the influence of the contraction is eliminated by the correction value, or the like has been opened (for example, refer to JP-A-2002-333744).
However, according to such a technique, since it is necessary to previously preset correction values with respect to all kinds of recording media capable of being used in the image forming apparatus, the operation is troublesome. A problem to be solved that since it is necessary to add a storing apparatus or the like, the apparatus becomes complicated and it results in an increase in costs still remains.
It is a problem to be solved that, particularly, in the case where the same image is printed onto both surfaces or onto the same surface, the positional change of the same image is likely to be conspicuous.